Abell 3560, a galaxy cluster at the edge of a major merging event

¹ INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
² Istituto di Radioastronomia del CNR, via Gobetti 101, 40129, Bologna, Italy
³ INAF – Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate (LC), Italy
⁴ European Southern Observatory, Karl-Schwartzschild-Strasse 2, 85748 Garching, Germany
⁵ Istituto di Fisica Cosmica “G. Occhialini” del CNR, via Bassini 15, 20133 Milano, Italy

Corresponding author: S. Bardelli, bardelli@bo.astro.it

Received: 17 May 2002
Accepted: 28 August 2002

Abstract

In this paper we study A3560, a rich cluster at the southern periphery of the A3558 complex, a chain of interacting clusters in the central part of the Shapley Concentration supercluster.
From a ROSAT-PSPC map we find that the X-ray surface brightness distribution of A3560 is well described by two components, an elliptical King law and a more peaked and fainter structure, which has been modeled with a Gaussian. The main component, corresponding to the cluster, is elongated with the major axis pointing toward the A3558 complex. The second component, centered on the Dumb-bell galaxy which dominates the cluster, appears significantly offset (by ~0.15 h^-1 Mpc) from the cluster X-ray centroid. 
From a Beppo-SAX observation we derive the radial temperature profile, finding that the temperature is constant (at  keV) up to 8 arcmin, corresponding to 0.3 h^-1 Mpc: for larger distances, the temperature significantly drops to  keV. We analyze also temperature maps, dividing the cluster into 4 sectors and deriving the temperature profiles in each sector: we find that the temperature drop is more sudden in the sectors which point towards the A3558 complex. 
From VLA radio data, at 20 and 6 cm, we find a peculiar bright extended radio source (J1332–3308), composed of a core (centered on the northern component of the Dumb-bell galaxy), two lobes, a “filament" and a diffuse component. The morphology of the source could be interpreted either by a strong interaction of the radio source with the intracluster medium or by the model of intermittency of the central engine.